Upper slewing bodies for a construction machine described in Japanese Unexamined Patent Publication Nos. 2000-54429 and 2000-248583 have been known. FIG. 4 in Japanese Unexamined Patent Publication No. 2000-54429 depicts an upper slewing body which includes an upper frame and a control valve provided on the upper frame, wherein the control valve is oriented obliquely to a lateral direction of the upper frame. Japanese Unexamined Patent Publication No. 2000-248583 describes a slewing hydraulically-driven working machine which includes a hydraulic pump, an oil tank, and an operation valve, the operation valve being obliquely disposed laterally and forward or rearward of the center of slewing. Furthermore, Japanese Unexamined Patent Publication No. 2000-248583 discloses, in the paragraph [0010] thereof, that the disposition of the operation valve allows each of pipes to be shortened to minimize a possible pressure loss.
Such an upper slewing body includes an upper frame, on which an engine as a driving source for the hydraulic pump and the like is mounted, in addition to the hydraulic pump, the control valve connected to the hydraulic pump, and the tank as described above. For such an upper slewing body, it is desirable to compactly arrange the elements to be mounted on the upper frame with a shortened hydraulic pipe connecting the hydraulic pump and the control valve together.